Wafer transport system

ABSTRACT

A substrate transport system includes a substrate cart inside a chamber and a linearly driven shuttle outside the chamber configured to levitate the substrate cart into a non contact, spaced relationship with respect to outwardly opposing sides of an interior wall of the chamber and to linearly drive the substrate cart within the chamber.

RELATED APPLICATIONS

This continuation application claims benefit of and priority to U.S. patent application Ser. No. 13/621,353 filed Sep. 17, 2012, which hereby claims benefit of and priority under 35 U.S.C. §119, 120, 363, 365 and 37 C.F.R. §1.55 and §1.78, which application claims benefit of and priority to U.S. Provisional Application Ser. Nos. 61/627,065 and 61/627,031 filed Sep. 16, 2011 under 35 U.S.C. §§119, 120, 363, 365, and 37 C.F.R. §1.55 and §1.78, each incorporated herein by this reference.

FIELD

The disclosed embodiment relates to wafer and other types of substrate processes.

BACKGROUND OF THE INVENTION

Wafers are typically handled in a vacuum environment to prevent contamination of the wafers and resulting electronic chips. Since motors and the like could result in contamination of the vacuum environment and the wafers, robot arms and structure used to handle wafers are designed so that all of the motors are outside the vacuum enclosure. See, e.g., U.S. Pat. No. 6,485,250 incorporated herein by this reference.

To transport wafers and other like substrates amongst different processing modules (e.g., load ports, load locks, transport chambers, processing modules, and the like), wafer carts are used. There have also been efforts to effect magnetic levitation in driving the wafer cart in a vacuum transport chamber.

In some designs, selectively energizeable electromagnets on one or more tracks outside the vacuum chamber interact with permanent magnets on a wafer cart inside the vacuum chamber to levitate and drive the wafer cart inside the vacuum chamber. See U.S. Pat. No. 4,624,617 incorporated herein by this reference. Controlling the wafer cart so it doesn't touch the vacuum chamber walls is difficult. See published U.S. Application No. 2009/0162179, incorporated herein by this reference. More advanced designs are highly complex, expensive, may be unreliable, and utilize a significant amount of energy. See U.S. Pat. Nos. 6,183,615 and 6,684,794 incorporated herein by this reference.

In other systems, a drive unit outside the vacuum has permanent magnets and so too does the wafer shuttle inside the vacuum chamber. See U.S. Pat. Nos. 7,841,820 and 4,805,761 incorporated herein by this reference. But, permanent magnet based systems necessarily results in a wafer shuttle which must contact the vacuum chamber walls. Contamination of the vacuum chamber and thus the wafers processed therein is thus possible through friction and wear of the contact surfaces.

SUMMARY

In one aspect, the wafer cart need not touch the vacuum chamber walls and yet the system is less complex and less expensive than prior systems. One unique aspect associated with one preferred embodiment features a vacuum chamber with a shape defining an interior rail for the wafer cart and an exterior tunnel for the shuttle. A portion of the wafer cart conforms to the vacuum chamber interior rail.

This invention features a substrate transport system comprising a chamber, a substrate cart inside the chamber, and a linearly driven shuttle outside the chamber. The linearly driven shuttle is configured to levitate the substrate cart into a non contact spaced relationship with respect to outwardly opposing sides of an interior wall of the chamber and to linearly drive the substrate cart within the chamber.

The substrate transport system could be a linearly driven shuttle which is driven by a lead screw coupled to the chamber or the shuttle may include a motor. The chamber wall could be a tunnel and with the substrate cart on opposing sides of the tunnel. A second substrate cart can be disposed on a common path with respect to the first substrate cart and linearly movable independent of the first substrate cart.

The linearly driven shuttle could have a magnetic subsystem with an active suspension portion and a passive coupling portion. The active suspension portion actively levitates the substrate cart into a non contact spaced relationship with respect to the interior wall of the vacuum chamber and the passive coupling portion is configured to passively linearly drive the substrate cart within the vacuum chamber. This embodiment of the substrate cart may comprise spaced ferromagnetic members.

Also featured is a substrate transport system comprising a substrate cart inside a vacuum chamber and a linearly driven shuttle outside the vacuum chamber configured to actively levitate the substrate cart into a non contact spaced relationship with respect to outwardly opposing sides of an interior wall of the vacuum chamber. The linearly driven shuttle is magnetically coupled to the substrate cart and is configured to linearly drive the substrate cart within the vacuum chamber. An interior wall forms a vacuum barrier between the linearly driven shuttle and inside the vacuum chamber. The linearly driven shuttle may be driven by a lead screw coupled to the chamber.

Also featured is a substrate transport system including a substrate cart inside a vacuum chamber, a linearly driven shuttle outside the vacuum chamber and linearly moveable with respect to the vacuum chamber. The linearly driven shuttle includes a magnetic subsystem with an active suspension portion and a passive coupling portion. The active suspension portion is configured to actively levitate the substrate cart into a non contact spaced relationship with respect to outwardly opposing sides of an interior wall of the vacuum chamber. The linearly driven shuttle is also passively magnetically coupled to a substrate cart with the passive coupling portion configured to passively linearly drive the substrate cart within the vacuum chamber. The interior wall may form a vacuum barrier between the linearly driven shuttle and inside the vacuum chamber.

The disclosed embodiments need not achieve all these objectives and the claims hereof should not be limited to structures or methods capable of achieving these objectives.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which:

FIG. 1 is a schematic top view of a simplified example of a wafer processing system including various modules;

FIG. 2 is a schematic view showing the rail and tunnel portion of the vacuum chamber transport module depicted in FIG. 1;

FIG. 3 is a schematic three dimensional view showing now the wafer cart inside the vacuum chamber about its rail and a linearly driven shuttle maneuverable in the tunnel defined by the vacuum chamber;

FIG. 4 is a schematic three dimensional front view of the wafer cart shown in FIG. 3;

FIG. 5 is a schematic three dimensional partially cut away view of an example of a linearly driven shuttle as depicted in FIG. 3;

FIG. 6 is a block diagram showing the primary components associated with the linearly driven shuttle as depicted in FIG. 5;

FIG. 7 is a highly pictorial view of the wafer cart and the shuttle depicted in FIGS. 4 and 5 showing the passive and active magnetic coupling techniques used in one preferred embodiment of the invention;

FIG. 8 is a schematic cross sectional depiction of another vacuum chamber featuring two wafer carts and two shuttles;

FIGS. 9A and 9B are schematic top views showing another example of a wafer transport system in accordance with the invention;

FIG. 10 is a schematic cross sectional view of a magnetic ball screw and magnetic array configured as a nut associated with the system of FIG. 9;

FIG. 11 is a schematic cross sectional front view of an example of a substrate transport platform in accordance with one embodiment;

FIGS. 12A and 12B are schematic views showing examples of different types of vacuum chamber configurations;

FIG. 13 is a schematic top view showing another example of a substrate transport system;

FIG. 14 is a schematic cross sectional view showing an example of a magnetic array fashioned as a wheel in accordance with the example of FIG. 13; and

FIGS. 15A and 15B are schematic top views showing the operation of the system of FIGS. 13 and 14.

DETAILED DESCRIPTION

The disclosed embodiment is capable of other embodiments and of being practiced or being carried out in various ways. Thus, it is to be understood that the disclosed embodiment is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. If only one embodiment is described herein, the claims hereof are not to be limited to that embodiment. Moreover, the claims hereof are not to be read restrictively unless there is clear and convincing evidence manifesting a certain exclusion, restriction, or disclaimer.

FIG. 1 depicts an example of wafer processing modules 12 a and 12 b, transport module 14, and load station 16, all of which typically constitute interconnected vacuum chambers. In this simplified example, processing chambers 12 a and 12 b may include robot arms. There may be many more modules and stations in a complete system.

FIG. 2 shows one particular vacuum chamber 14 defining exterior tunnel 20 forming interior rail 22. Wafer cart 24, FIG. 3 is disposed inside vacuum chamber 14 and is configured with shoe 26 shaped about vacuum chamber rail 22. In this specific example, rail 22 is a curved convex structure and shoe 26 is a curved concave structure. Shuttle 30 levitates cart 24 into a non-contact spaced relationship with respect to interior wall 22 of chamber 14 and linearly drives shuttle 24 within chamber 14.

Shuttle 30 is preferably linearly driven and resides outside vacuum chamber 14 and travels to and fro in tunnel 20. Shuttle 30 and wafer cart 24 are configured such that wafer cart 24 is levitate by shuttle 30 (shoe 26 is spaced from rail 22) and follows shuttle 30 as it travels in tunnel 20.

In this way, a wafer or other like substrate on supports 32 a-32 d on the top surface of wafer cart 24 can be transported, for example, from load lock 16, FIG. 1 to station 12 b via vacuum chamber 14. In other examples, wafer cart 24 is equipped with one or more movable maneuvering wafer arms. See, for example, U.S. Pat. No. 7,901,539 incorporated herein by this reference.

In one preferred design as shown in FIGS. 3-4, the wafer cart shoe walls 32 a, 32 b; the tunnel walls 34 a, 34 b; and optionally the shuttle walls 36 a, 36 b are configured in a concentric design as shown so, for example, shuttle wall 36 a is fairly close to and shaped the same as wafer cart wall 32 a and yet separated therefrom by vacuum chamber barrier wall 34 a.

Now, with electromagnetic and permanent magnets in the shuttle walls and ferromagnetic material in the wafer cart walls, the wafer cart can be elevated within the vacuum chamber slightly above rail 22 and driven to and fro in vacuum chamber 14, and also controlled so that the shuttle does not touch the vacuum chamber.

For example, here shuttle wall 36 is made of non-magnetic material such as stainless steel. Set in shuttle wall 36 b are fore and aft electromagnets 40 a and 40 b and permanent magnet 42 a. Shuttle wall 36 a is configured similarly. Non-magnetic wafer cart wall 32 a has spaced ferromagnetic (e.g., iron) members 50 a, 50 b, 50 c as does wall 32 b.

Shuttle permanent magnets 42 a and wafer cart ferromagnetic member 50 b are configured to levitate the wafer cart off the vacuum chamber rail and to urge the wafer cart to follow the shuttle.

To control the orientation of the wafer cart, the electromagnets are used in conjunction with the ferromagnetic elements in the wafer cart walls. For example, if the left hand side of the wafer cart (e.g., wall 32 a) starts to get too close to rail 22 (and wall 34 a) as determined by position sensors, then both electromagnets 40 a and 40 b are energized, pulling wall 32 b of the wafer cart closer to vacuum chamber wall 34 b and driving wafer cart wall 32 a away from vacuum chamber wall 22 and also centering the wafer cart in a spaced relationship with respect to the vacuum chamber rail. Energizing only one shuttle electromagnet (or alternate side, different position electromagnets) would change the yaw angle of the wafer cart.

In this way, with only four electromagnets and two permanent magnets, the wafer cart yaw, pitch, and roll can be controlled. For example, if the wafer cart is pitched down in the front, rear shuttle electromagnets 40 a can be energized. If the wafer cart rolls to the right, left hand side electromagnets can be energized to correct the roll.

And, the wafer cart is designed to remain sterile. Shuttle 30, FIG. 5 contains the linear drive mechanism(s), the position sensors, the driven magnetic coils, the power supply, the controlling electronics and the like but shuttle 30 is outside of the vacuum chamber. One exemplary drive mechanism 59 includes belt 60 fixed on one or both ends and driven by motor drive 62 between free spinning pulleys 64 a and 64 b. Other drive mechanisms are possible.

Another drive mechanism for shuttle 30 is a lead or ball screw arrangement for a magnetic screw. See, for example, U.S. Pat. No. 6,712,907 incorporated herein by this reference.

Shuttle 30, FIG. 6 includes a drive subsystem 59 as just disclosed, power supply 70, an electromagnetic subsystem 72, a sensor subsystem 74, and controller 76. Controller 76 (e.g., a microcontroller, application specific integrated circuit, or the like), based on the output of sensor subsystem 74, controls both drive subsystem 59 and, as discussed above, the electromagnetic subsystem 72 to control the orientation of the wafer cart with respect to the vacuum chamber rail. Control and positioning of the vacuum wafer cart based on position sensors and electromagnets is noted in published U.S. Application No. 2009/0162179, incorporated herein by this reference.

FIG. 7 shows again wafer cart 24 and shuttle 30 and the respective permanent magnets (42), electromagnets (40) and ferromagnetic members (50). The interaction between the shuttle electromagnetics and the wafer cart ferromagnetic members is active coupling while the interaction between the shuttle permanent magnets and the wafer cart ferromagnetic members is passive coupling as depicted in the figure. The vectors shown show how active control F_(LFy) and F_(RFy) control y_(F) and F_(LFy) and F_(RRy) control y_(R) for guidance and yaw control. Passive coupling means F_(Lx) and F_(Rx) control x for propulsion and R_(LFz), F_(RFz), F_(LRz), and F_(RRz) control z and Ry for lift, pitch, and roll control.

FIG. 8 shows a dual shuttle configuration where vacuum chamber 14 includes two independently driven substrate carts 24 a and 24 b each with conforming shoes 26 a and 26 b. Vacuum chamber 14 defines dual rails 22 a and 22 b and two independently driven shuttles 30 a and 30 b are shown. Wafer cart 24 a supports substrate 80 b on top surface 82 a a portion of which extends over wafer cart 24 b as shown. Wafer cart 24 b supports wafer 80 b on top surface 82 b which extends horizontally from vertically disposed arm 86. Cutouts such as cutout 90 is for weight savings and/or balance control.

The result is one or more wafer carts that do not touch the vacuum chamber walls and yet the system is less complex and less expensive than prior systems. In one aspect, irrespective of the specific shape or shapes or configurations, the preferred vacuum chamber forms an interior rail of a sort with a tunnel in it for travel of the exterior shuttle. The wafer cart inside the vacuum chamber has a shoe portion shaped conformably about the vacuum chamber rail. A magnet subsystem is associated with at least the shuttle and is configured to levitate the wafer cart conformal shoe into a spaced relationship with respect to the vacuum chamber interior rail, to adjust the orientation of the wafer cart with respect to the rail, and to drive the wafer cart in the vacuum chamber with the shuttle outside the vacuum chamber in the tunnel.

In other designs, the shuttle in the tunnel is or includes one or more magnetic ball screws. FIGS. 9A and 9B show a design with two magnetic ball screws 110 a and 110 b outside the vacuum environment and magnetic arrays configured as nuts 114 a and 114 b within the vacuum environment magnetically linearly driven by screws 110 a and 110 b, respectively. See also FIG. 10. The nuts support frame members 102 a and 102 b. In FIG. 9A, driving both screws in the same direction linearly drives frame members 102 a and 102 b within the vacuum chamber. Driving the screws in the opposite direction can cause an arm on the frame members to rotate, or the like.

The contactless lead screw mechanism(s) may be utilized to convert rotary motion to linear motion, and vice versa without the negative aspects of mechanical contact, such as the presence of friction, the need for lubrication, generation of particles and sensitivity to aggressive environments associated with conventional lead screws and ball screws. Therefore, due to its cleanliness of operation, the contactless lead screw mechanism may be suitable for clean and vacuum applications and, due to its resistance to aggressive agents, for harsh environments where conventional solutions fail. The present contactless lead screw mechanism of one or more embodiments of this invention may be utilized in a material transport system, e.g., to produce linear motion of a material transport platform.

As shown in FIG. 10, the contactless lead screw mechanism may include a lead screw component 110 with threads having a thread pitch and one or more nut components 114 with threads having substantially the same thread pitch as the pitch of the screw. The lead screw component may include a body of a substantially cylindrical shape and thread-type features on the cylindrical body made of a ferromagnetic material. The thread-type features may be made of a solid piece, assembled from multiple pieces, laminated from multiple sheets to reduce eddy current losses, formed from powder metal or produced in any other suitable manner. The lead screw component may be constrained so that it is allowed to rotate with respect to the axis of its cylindrical body or tunnel, e.g., by utilizing one or more rotary bearings, with respect to the nut component(s). Each nut component 114 may include a body, made of one or more parts, with a substantially hollow cylindrical cavity, which may feature a thread-type arrangement made of a ferromagnetic material and compatible with the thread-type features on the lead screw component. The thread-type arrangement may be made of a solid piece, assembled from multiple pieces, laminated from multiple sheets to reduce eddy current losses, or produced in any other suitable manner. Each nut may also feature one or more magnets located so that a magnetic circuit is closed through the thread-type arrangement of the nut component and the thread-type features of the lead screw component. The magnets may be permanent magnets, electrically activated magnets or any magnets of any suitable type.

In an alternative embodiment, the magnet(s) of the nut component may interact directly with the thread-type features of the lead screw component. In yet another embodiment, the magnet(s) may be incorporated into the lead screw component. Each nut component may be constrained so that it is allowed to translate along the axis of the cylindrical body of the lead screw component, e.g., by utilizing one or more linear bearings, with respect to the lead screw component. A separation vacuum chamber wall made of a non-ferromagnetic material, which may, for example, be of a cylindrical shape, may be present between the ball screw component and the nut component(s).

When the lead screw component is caused to rotate, the magnetic field produced by the magnets results in magnetic forces between the thread-type features of the lead screw component and the thread-type arrangement of the nut component(s). This causes the nut component(s) to move linearly along the axis of the cylindrical body of the lead screw component. The separation wall between the lead screw component and the nut component(s) may be utilized to separate the environment where the lead screw component is located from the environment of the nut component(s). For example, the lead screw component may be located in atmosphere and the nut component(s) may be located in vacuum.

Numerous industrial applications, including transportation and positioning systems, require a platform that can move along a straight-line path while carrying an actively driven mechanism, such as a robotic arm. The moveable platform according to one or more embodiments of this present invention may provide this functionality with no on-board active components, such as power management solutions, control electronics and actuation arrangements. As a result, the moveable platform of this invention may be suitable for applications where the presence of active components on the moveable platform is undesirable, for instance, due to issues with heat removal, such as in vacuum environments.

As shown in FIG. 9, the moveable platform according to the one embodiment of this invention may include a body, which may be constrained to move along a straight-line path, for example, by utilizing one or more linear bearings or a magnetic levitation system. One or more magnetic nut components may be rigidly or moveably coupled to the body. One or more lead screw components may be arranged along the direction of motion of the body, for example, on the side of the body, below the body, above the body or in any suitable manner, so that the axes of rotation of the worm components are substantially parallel with the direction of motion of the body. Each of the lead screw components may interact with one or more nut components through magnetic forces, forming one or more contactless lead screw mechanisms. Separation walls made of a non-ferromagnetic material may be present between the nut component(s) and the lead screw component(s).

An example of the moveable platform of one or more embodiments of this invention may include a body with a first nut component attached rigidly to the body and a second nut component coupled moveably to the body, e.g., through a linear bearing. A first lead screw component may be utilized to interact with the first nut component, and a second lead screw component may be utilized to interact with the second nut component. When the first and second lead screw components rotate in the same direction, the first nut causes the body of the platform to move and the second nut moves with the body in the same manner as the body. If the first lead screw component is kept stationary and the second lead screw component rotates, the first nut component and, therefore, the body remain stationary while the second nut component moves relative to the body. Any combination of translation of the body and relative motion of the second nut component with respect to the body may be achieved by properly coordinated rotation of the two lead screw components. In this way, a substrate cart body can be driven linearly and an arm on the substrate cart body can be rotated.

The arrangement discussed above may be utilized to realize a moveable platform that may carry a robotic arm driven by the relative motion of the second nut component with respect to the body. When the lead screw components rotate in the same direction, the entire platform translates with no motion of the robotic arm with respect to the body of the platform. By rotating the second lead screw component while the first lead screw component is kept stationary, the robotic arm may be operated while the body of the platform remains stationary. The arm may be operated simultaneously while the body of the platform moves by properly coordinated rotation of the two lead screw components. Separation walls between the nut components and the lead screw components may be utilized to separate the environments) where the body and robotic arm operate and where the lead screw components are located. For example, since the body and robotic arm are completely passive, they may be located in a vacuum environment while the lead screw components may conveniently stay in atmosphere. Additional degrees of freedom of the robotic arm may be realized by employing additional nut and lead screw components.

FIG. 11 shows a substrate cart platform 100 with frame 102. Arm 104 a is rotatable with respect frame 102 via linear drive 105 a and bearing 107. Arm 104 b is rotatable with respect to arm 104 a via pulley 108. Arm 104 c is rotatable with respect arm 104 b via pulley 109. The cart platform is linearly driven. Thus, here, three degrees of freedom are possible.

Here, there are three ball screw shafts 110 a, 110 b, and 110 c each independently driven by a servomotor and belt/pulley set or the like. Each ball screw resides in a tunnel in the vacuum chamber and is thus isolated from the wafer environment.

Rotating ball screw 110 a linearly actuates drive 105 a and rotates arm 104 b extending and retracting arms 104 b and 104 c. Rotating all three ball screws 110 a, 110 b, and 110 c linearly moves frames 102 and its arms. Rotating ball screws 110 a and 110 b rotates arm 104 a.

Linear drive 105 b is linearly activated by rotating ball screw 110 c and linearly actuating drive 105 b rotates pulley 112 which rotates arm 104 b. Pulley 112 is rotatable with respect to frame 102 via bearing 114. Linear drives 105 a and 105 b may drive their respective arms 104 a and pulley 112 via rack and pinion interfaces, for example.

The linear drives include nuts 114 magnetically driven by their respective ball screw shafts. The nuts may include magnetic arrays as shown in and/or as discussed above with respect to FIG. 10 and/or as shown in U.S. Pat. No. 6,712,907 incorporated herein by this reference. Such nuts are within the vacuum environment.

FIG. 12A shows a portion of a vacuum chamber with three non-magnetic vacuum barrier sleeves such as tunnels 120 a, 120 b, and 120 c for the three screw shafts of FIG. 9. FIG. 12B shows an embodiment where two tunnels 120 a′ and 120 b′ are not full tubes.

FIG. 13 shows a design where motors 140 a and 140 b rotate magnetic screw shafts 142 a and 142 b, respectively, in vacuum chamber tunnels 120 a and 120 b (see FIG. 10), respectively. Frame 102′ within the vacuum chamber supports one or more arms (see FIG. 9) or serves as a wafer cart (see FIG. 3). Magnetic arrays, formed as gears or wheels 150 a and 150 b are coupled to frame 102′ and magnetically interact with shafts 142 a and 142 b to rotate and linearly drive frame 102′. See also FIG. 14.

This contactless worm drive mechanism may be utilized to transmit rotary motion, and typically provide speed reduction, from one component to another component with rotational axes at 90 degrees to each other without the negative aspects of mechanical contact, such as the presence of friction, the need for lubrication, generation of particles and sensitivity to aggressive environments, associated with conventional worm drives. Therefore, due to its cleanliness of operation, the present contactless worm drive mechanism of one or more embodiments of this invention may be suitable for clean and vacuum applications and, due to its resistance to aggressive agents, also for harsh environments where conventional solutions fail. As an example application, the present contactless worm drive mechanism may be utilized in a material transport system, for instance, to actuate a material transport platform and its components.

As shown in FIG. 14, the contactless worm drive mechanism of one or more embodiments of this invention may include a worm component 142 and one or more warm wheel components 150. The worm component may include a body of a substantially cylindrical shape and thread-type features on the cylindrical body made of a ferromagnetic material. The thread-type feature may be made of a solid piece, assembled from multiple pieces, laminated from multiple sheets to reduce eddy current losses, formed from metal powder or produced in any other suitable manner. The worm component may be constrained so that it is allowed to rotate with respect to the axis of its cylindrical body, for instance, by utilizing one or more rotary bearings, with respect to the worm wheel component(s). Each worm wheel component may include a substantially cylindrical body, which may feature tooth-type arrangements made of a ferromagnetic material and may be geometrically compatible with the thread-type features on the worm component. The tooth-type arrangements may be made of a solid piece, assembled from multiple pieces, laminated from multiple sheets to reduce eddy current losses, or produced in any other suitable manner. Each worm wheel component may also feature one or more magnets located so that a magnetic circuit is closed through the tooth-type arrangements of the worm wheel component and the thread-type features of the worm component. The magnets may be permanent magnets, electrically activated magnets or other magnets of any suitable type. In an alternative embodiment of this invention, the magnet(s) of the worm wheel component may interact directly with the thread-type features of the worm component. In yet another embodiment, the magnet(s) may be incorporated into the worm component. Each worm wheel component may be constrained so that it is allowed to rotate with respect to an axis perpendicular to the axis of the cylindrical body of the worm component, for instance, by utilizing one or more rotary bearings, with respect to the worm component. A separation wall made of a non-ferromagnetic material, which may, for example, be of a cylindrical shape, may be present between the worm component and the worm wheel component(s).

When the worm screw component is caused to rotate, the magnetic field produced by the magnets results in magnetic forces between the thread-type features of the worm component and the tooth-type arrangements of the worm wheel component(s), causing the worm wheel component(s) to rotate, typically at a reduced speed, allowing for higher torque. The separation wall 120 between the worm component and the worm wheel component(s) may be utilized to separate the environment where the worm component is located from the environment of the worm wheel component(s). For example, the worm component may be in atmosphere and the worm wheel component(s) in vacuum.

Numerous industrial applications, including transportation and positioning systems, may require a platform that can move along a straight-line path while carrying an actively driven mechanism, such as a robotic arm. The moveable platform 102′, FIGS. 15A and 15B may provide this functionality with no on-board active components, such as power management solutions, control electronics and actuation arrangements. As a result, the moveable platform may be suitable for applications where the presence of active components on the moveable platform is undesirable, for instance, due to issues with heat removal, such as in vacuum environments.

The moveable platform may include of a body, which may be constrained to move along a straight-line path, for example, by utilizing one or more linear bearings or a magnetic levitation system. One or more magnetic worm wheel components 150 a and 150 b may be pivotably coupled to the body. One or more wood components may be arranged along the direction of motion of the body, for example, on the side of the body, below the body, above the body or in any suitable manner, so that the axes of rotation of the worm components are substantially parallel with the direction of motion of the body. Each of the worm components may interact with one or more worm wheel components through magnetic forces, forming one or more contactless worm drives. Separation walls made of a non-ferromagnetic material may be present between the worm wheel component(s) and the worm component(s).

As shown in FIG. 15, an exemplary embodiment of a moveable platform according to one embodiment of this invention may include a body with a single worm wheel component and two worm components interacting with the worm wheel component on the opposite sides of the worm wheel component. When the worm components are caused to rotate in the same direction, FIG. 15A the worm wheel component does not rotate and translates along the direction of motion of the body of the platform, moving the body of the platform in the desired direction of motion. If the direction of rotation of both worm components is reversed, the body reverses the direction of motion as well.

When the worm components rotate in opposite directions with respect to each other, FIG. 15B the center of the worm wheel component and, therefore, the body remain stationary while the worm wheel component rotates with respect to the body. If the direction of motion of each of the worm components is reversed, the rotation of the worm wheel component also reverses. Any combination of translation and rotation of the worm wheel component may be achieved by properly coordinated rotation of the two worm components.

The above described arrangement may be utilized to realize a moveable platform that may carry a robotic arm driven by the worm wheel component. When the worm components rotate in the same direction, the entire platform translates with no motion of the robotic arm with respect to the body of the platform. The worm components may be driven to rotate in the opposite directions to operate the robotic arm while the body of the platform remains stationary. The arm may be operated simultaneously while the body of the platform moves by properly coordinated rotation of the two worm components. Separation walls between the worm wheel component and the two worm components may be utilized to separate the environment(s) where the body and robotic arm operate and where the worm components are located. For example, since the body and robotic arm are completely passive, they may be located in a vacuum environment while the driven worm components may conveniently stay in atmosphere. Additional degrees of freedom of the robotic arm may be realized by employing additional worm drives.

Although specific features of the invention are shown in some drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. The words “including”, “comprising”, “having”, and “with” as used herein are to be interpreted broadly and comprehensively and are not limited to any physical interconnection. Moreover, any embodiments disclosed in the subject application are not to be taken as the only possible embodiments.

In addition, any amendment presented during the prosecution of the patent application for this patent is not a disclaimer of any claim element presented in the application as filed: those skilled in the art cannot reasonably be expected to draft a claim that would literally encompass all possible equivalents, many equivalents will be unforeseeable at the time of the amendment and are beyond a fair interpretation of what is to be surrendered (if anything), the rationale underlying the amendment may bear no more than a tangential relation to many equivalents, and/or there are many other reasons the applicant can not be expected to describe certain insubstantial substitutes for any claim element amended.

Other embodiments will occur to those skilled in the art and are within the following claims. 

What is claimed is:
 1. A substrate transport system comprising: a chamber; a substrate cart inside the chamber including one or more magnetic arrays configured as nuts; and one or more lead screws coupled to the chamber configured to drive the magnetic arrays to linearly drive the substrate cart within the chamber.
 2. The substrate transport system of claim 1 in which the chamber is configured as a vacuum environment.
 3. The substrate transport system of claim 1 in which the chamber further comprises a separation wall between the one or more lead screws and the one or more magnetic arrays.
 4. The substrate transport system of claim 1 in which the one or more lead screws are configured magnetic screws.
 5. The substrate transport system of claim 4 in which the magnetic screws are configured to magnetically drive the nuts.
 6. The substrate transport system of claim 1 in which each said nuts is configured to support a frame member.
 7. The substrate transport system of claim 6 in which driving a plurality of the lead screws in the same direction linearly drives the frame member within the chamber.
 8. The substrate transport system of claim 6 in which driving a plurality of the lead screws in the opposite direction causes an arm on the frame members to rotate.
 9. The substrate transport system of claim 1 in which one or more lead screws is configured in a non contact spaced relationship with respect to the one or more magnet arrays.
 10. The substrate transport system of claim 1 in which the chamber includes one or more vacuum barrier sleeves configured to house the one or more lead screws.
 11. The substrate transport system of claim 1 in which one or more lead screws includes threads having a thread pitch
 12. The substrate transport system of claim 11 in which the nuts include threads having substantially the same thread pitch as the lead screws.
 13. The substrate transport system of claim 12 in which the threads of one or more lead screws are made of a ferromagnetic material.
 14. The substrate transport system of claim 13 in which the threads of nuts are made of a ferromagnetic material compatible with the magnetic material of the threads of the one or more lead screws.
 15. The substrate transport system of claim 14 in which rotation of the one or more lead screws generates a magnetic field which results in magnetic forces between the threads of the one or more lead screws and the threads of the nuts thereby causing the nuts to move linearly along an axis of the one or more lead screws. 